Zn Subcellular Distribution in Liver of Goldfish (Carassius Auratus) with Exposure to Zinc Oxide Nanoparticles and Mechanism of Hepatic Detoxification

Wenhong Fan,Qian Li,Xiuping Yang,Li Zhang,Qinghua Sun

doi:10.1371/journal.pone.0078123

Wenhong Fan, Qian Li + Show 3 more

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https://doi.org/10.1371/journal.pone.0078123

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Abstract

Zinc Oxide Nanoparticles (ZnO NPs) have attracted increasing concerns because of their widespread use and toxic potential. In this study, Zn accumulations in different tissues (gills, liver, muscle, and gut) of goldfish (Carassius auratus) after exposure to ZnO NPs were studied in comparison with bulk ZnO and Zn2+. And the technique of subcellular partitioning was firstly used on the liver of goldfish to study the hepatic accumulation of ZnO NPs. The results showed that at sublethal Zn concentration (2 mg/L), bioaccumulation in goldfish was tissue-specific and dependent on the exposure materials. Compared with Zn2+, the particles of bulk ZnO and the ZnO NPs appeared to aggregate in the environmentally contacted tissues (gills and gut), rather than transport to the internal tissues (liver and muscle). The subcellular distributions of liver differed for the three exposure treatments. After ZnO NPs exposure, Zn percentage in metal-rich granule (MRG) increased significantly, and after Zn2+ exposure, it increased significantly in the organelles. Metallothionein-like proteins (MTLP) were the main target for Zn2+, while MRG played dominant role for ZnO NPs. The different results of subcellular distributions revealed that metal detoxification mechanisms of liver for ZnO NPs, bulk ZnO, and Zn2+ were different. Overall, subcellular partitioning provided an interesting start to better understanding of the toxicity of nano- and conventional materials.

Highlights

In recent years, following the mass production and widespread use of nanomaterials, their toxic effects have attracted increased concerns because of their substantially different properties from traditional materials [1,2]
The main objective of this study is to investigate whether the fish toxicity of Zinc Oxide Nanoparticles (ZnO NPs) was size- or composition- related by comparing the NPs to their bulk counterparts
The ZnO NPs and bulk ZnO stock suspensions (100 mg/L) were prepared as follows: 100 mg ZnO NPs or bulk ZnO particles were transferred to 1 L ultra-pure water (Barnstead, EASYpure II, USA) and dispersed using a ultrasonic cleaner for at least 30 min to break them into small particles

Summary

Introduction

In recent years, following the mass production and widespread use of nanomaterials, their toxic effects have attracted increased concerns because of their substantially different properties from traditional materials [1,2]. Zinc Oxide Nanoparticles (ZnO NPs), one of the most widely used nanomaterials, are already produced in industrial scale [3,4]. It will certainly be used more widely in different industries as a result of their unique advantages in industrial and medicinal products. Direct and indirect releases of nanoparticles (NPs) into aquatic environments via engineering applications and sewage effluent will increase the exposure of humans and ecosystems to NPs. the potential effects of ZnO NPs on aquatic ecosystems have attracted special attentions [5,6]. The generally accepted toxicity mechanisms of ZnO NPs include particle effects and dissolved free-ion effects [10]. The environmental behavior and biological effects of ZnO NPs are complicated and unpredictable

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